/*
 * Copyright 2002-2007 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.beans.factory.xml;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.core.io.Resource;

/**
 * Convenience extension of {@link DefaultListableBeanFactory} that reads bean
 * definitions from an XML document. Delegates to
 * {@link XmlBeanDefinitionReader} underneath; effectively equivalent to using
 * an XmlBeanDefinitionReader with a DefaultListableBeanFactory.
 * 
 * <p>
 * The structure, element and attribute names of the required XML document are
 * hard-coded in this class. (Of course a transform could be run if necessary to
 * produce this format). "beans" doesn't need to be the root element of the XML
 * document: This class will parse all bean definition elements in the XML file.
 * 
 * <p>
 * This class registers each bean definition with the
 * {@link DefaultListableBeanFactory} superclass, and relies on the latter's
 * implementation of the {@link BeanFactory} interface. It supports singletons,
 * prototypes, and references to either of these kinds of bean. See
 * "spring-beans-2.0.dtd" for details on options and configuration style.
 * 
 * <p>
 * <b>For advanced needs, consider using a {@link DefaultListableBeanFactory}
 * with an {@link XmlBeanDefinitionReader}.</b> The latter allows for reading
 * from multiple XML resources and is highly configurable in its actual XML
 * parsing behavior.
 * 
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @since 15 April 2001
 * @see org.springframework.beans.factory.support.DefaultListableBeanFactory
 * @see XmlBeanDefinitionReader
 */
public class XmlBeanFactory extends DefaultListableBeanFactory {

	// #Comment#:为容器定义了一个默认的Bean定义读取器。
	private final XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader(this);

	/**
	 * 根据指定的资源（必须是可以使用DOM解析的），创建一个性的XmlBeanFactory。<br/>
	 * Create a new XmlBeanFactory with the given resource, which must be
	 * parsable using DOM.
	 * 
	 * @param resource
	 *            XML resource to load bean definitions from
	 * @throws BeansException
	 *             in case of loading or parsing errors
	 */
	public XmlBeanFactory(Resource resource) throws BeansException {
		this(resource, null);
	}

	/**
	 * 根据指定的输入流（必须是可以使用DOM解析的），创建一个性的XmlBeanFactory。<br/>
	 * Create a new XmlBeanFactory with the given input stream, which must be
	 * parsable using DOM.
	 * 
	 * @param resource
	 *            XML 资源，用它来加载Bean定义<br/>
	 *            XML resource to load bean definitions from
	 * @param parentBeanFactory
	 *            父Bean工厂<br/>
	 *            parent bean factory
	 * @throws BeansException
	 *             in case of loading or parsing errors
	 */
	public XmlBeanFactory(Resource resource, BeanFactory parentBeanFactory)
			throws BeansException {
		super(parentBeanFactory);
		this.reader.loadBeanDefinitions(resource);
	}

}
